


pt. or agricui 

OEPT CIRCULA 



s.f v tvi .br 



231. 



FOREST 




LABORATORY 



MADISON 
WISCONSIN 




UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT CIRCULAR 231 

Washington, D. C. June, 1922 

(Issued April, 1922, as an unnumbered pamphlet) 



ADDITIONAL COPIES 

OF THIS PUBLICATION MAY BE PROCURED FROM 

THE SUPERINTENDENT OF DOCUMENTS 

GOVERNMENT PRINTING OFFICE 

t WASHINGTON, D. C. 

AT 

15 CENTS PER COPY 



I D^ 



1\5 

FOREST PRODUCTS 
LABORATORY 



A BRIEF ACCOUNT OF ITS WORK AND AIMS 



npHE FOREST PRODUCTS LABORATORY is a unit in the 
Branch of Research of the Forest Service, United States De- 
partment of Agriculture. It is located at Madison, Wis., and is 
conducted in cooperation with the University of Wisconsin. 

Public Service, 

/ T V HE purpose of the Forest Service in the adminis- 
tration of the Forest Products Laboratory is to 

conserve American forests by developing the most ,P e of 

. v • Activities. 

economical methods of converting standing trees into 

finished products. The purpose is also to make the 
growing of timber more profitable by increasing the 
possibilities in the utilization of both used and unused 
species. The Laboratory seeks to develop not only 
new and more efficient processes, but to find ways of 
utilizing material which would otherwise be wasted, 
to find new uses for old materials and new materials 
for old uses. In a word, the aim is to render practical 
assistance to the manufacturers and users of wood and 
wood products and at the same time to promote forest 
conservation and the practice of forestry. 

Every American industry and class of consumers 
which uses or grows wood or any other product of 
the forest may thus be a beneficiary of the work done 
at the Laboratory. Every such industry, class of con- 
sumers, and timber producers is a potential cooperator 
in the Laboratory's work. Its objects are sought not 
only through experiments conducted at the Laboratory 
but also through the detail of its men to work on 



4 Forest Products Laboratory. 

important problems in the mills and factories and the 
receiving of representatives of the industries at the 
Laboratory to work beside its scientific men. 

Value of y^g va l ue f tn i s work has already made itself 

Work. 

apparent. The reduction of waste, the better utiliza- 
tion of the products of the tree, the utilization of 
species hitherto wasted, the added life given to many 
kinds of wood products by more efficient preservative 
methods, the reduction of the degrade in lumber by 
efficient dry-kiln methods, and many other savings are 
an enormous help in conserving our timber supply. 
The financial advantage to industries and consumers 
may be indicated by an example. If the methods of 
nailing boxes recommended by the Forest Products 
Laboratory and adopted by the National Association 
of Box Manufacturers saves but 1 per cent of the 
annual loss for claims and damages in shipments 
actually paid by the railroads, the saving will be 
31,000,000 a year. It has been estimated that the 
total annual saving as a result of the work of the 
Laboratory has already reached not less than $30,- 
000,000. 

Results The value of the Forest Products Laboratory to any 

Available to , 1 • • 1 1 r 

P blic particular wood-using industry or class of consumers 

depends to a very large extent upon the use which that 

industry makes of it. It is a Government institution 

supported mainly by Government appropriations, and 

its advice and suggestions are to be had for the asking. 

It presents an opportunity for every manufacturer, 

user, and timber grower to supplement the information 

obtained by experience and hard knocks, with technical 

data obtained through scientific research. 

Place in y^ e wor k of the Laboratory is of direct value to 

Forest Con- .... . . ,-,-. , 

those engaged in timber production, lo a very large 

extent, the kinds and sizes of forest trees which should 

be grown and the purposes for which they should be 

produced are dependent on the mechanical, physical, 

and chemical properties of their woods and the uses to 



servation. 



Forest Products Laboratory. 




The largest of the testing machines, shown here in the process of erection, is capable of exerting a 
force of a million pounds and can test to destruction wooden columns 30 feet long and a foot 
square. 



6 Forest Products Laboratory. 

which they can most profitably be put. In the admin- 
istration of the National Forests and of privately 
owned timberlands, in the activities of the State For- 
estry departments, and in the instruction given by the 
forest schools, the results secured by the Laboratory 
play an important part. By reducing the present 
waste of three-fourths of every tree cut and making 
possible the most efficient utilization of the one-fourth 
used they are contributing in a very essential way to 
forest conservation and to profitable timber production. 
Through its forest products research the Forest Service 
supplements its efforts to bring about the growing of 
timber by information which should make possible the 
most complete and effective utilization. 

Allied In the 11 years the Laboratory has been in operation 

it has accumulated a vast store of fundamental infor- 
mation about the mechanical, physical, and chemical 
properties of wood. It has also studied the application 
of this information to the problems involved in the 
manufacture of wood products and chemical products 
derived from wood. In studying manufacturing prob- 
lems, materials used with the wood often require as 
much attention as the wood itself. This has necessi- 
tated the study of such subjects as glues, moisture- 
proof coatings, wood preservatives, laminated wood, 
and fire-retarding materials. 

Laboratory The Forest Products Laboratory was established in 

fnT^lO 511 ^ 1910 ^ the United States Forest Service at Madison, 
Wis., in cooperation with the University of Wisconsin. 

For several years it was the only institution of its kind 

in the world conducted with the object of turning the 

searchlight of research upon wood and its uses and 

making the information thus obtained available to the 

public. . . .; 

In this publication is presented a general outline of 

the aims and scope of work of the organization. 




R 



Organization for Research. 

ESEARCH is increasingly effective in proportion ( 



nated Re- 

as it is carefully planned and executed. At the searc h. 
beginning of each year a program covering as nearly 
as practicable the work of the Laboratory for the 
ensuing year is considered and approved. Individual 
initiative and responsibility are given the widest pos- 
sible opportunity, but at the same time the work of 
different men is so coordinated by an interchange of 
ideas among the different sections, and other means, 
that duplication is avoided and cumulative results are 
obtained. 

A carefully worked out system for keeping a check 
on the status, progress, and correlation of investigative 
activities and for guiding interrelated projects through 
the Laboratory has been adopted. Systematically 
planned programs and carefully coordinated type of 
organization is in a large measure responsible for the 
practical value of the work already accomplished. 

The Laboratory is in charge of a director, an assistant Organi- 

director, and a staff comprised of the heads of the ^ at J° n ° l e 

. . . . Laboratory, 

different research and administrative sections. In each 

section are men of broad general experience with wood 
and knowledge of its characteristics, and other special- 
ists in various wood uses, who devote their whole time 



Forest Products Laboratory. 

to the study of special problems. These men are 
recruited, in accordance with the regulations of the 
Civil Service Commission, from the professions of engi- 
neering, chemistry, forestry, and pathology. A sharp 
distinction is drawn between administrative and investi- 
gative assignments. In this way, research men are re- 
lieved of other cares and can give their whole thought 
to the problems in hand. 

The work of the Laboratory is distributed among 
the following technical sections: 

Timber mechanics. — Strength of wood and manufac- 
tured articles. 

Timber physics. — Experimental and applied kiln- 
drying, physical properties, identification, and struc- 
ture of wood. 

Wood preservation. — Wood treatments, glues, and 
laminated construction. 

Pulp and paper. — Manufacturing methods and suit- 
ability of various woods for pulp, paper, and special 
products. 

Derived products. — Chemical properties and uses of 
wood and chemical wood products, such as turpentine, 
alcohol, acetic acid, etc. 

Industrial investigations. — Methods and practices in 
the lumber and other wood-using industries, grades, 
specifications, and mill scale studies. 

Pathology (in cooperation with the Bureau of Plant 
Industry). — Decay of timber, molds, stains in manu- 
factured wood products, and antiseptic properties of 
wood preservatives. 

In addition, there is a section of Laboratory opera- 
tions which handles the administrative work involved 
in accounting, engineering, photography, computing, 
records, supplies, and the maintenance of the Labora- 
tory generally. A division in the director's office 
reviews and coordinates the results secured, prepares 
material for publication, and in other ways arranges 
for its most effective dissemination and utilization. 



Forest Products Laboratory. 9 

The work of each technical section is divided into Projects, 
"projects," each of which is assigned to one or more 
of the staff. Before one of these projects is undertaken 
a preliminary investigation is made and a report pre- 
pared indicating the nature of the problem, the work 
done, and results already secured in the same field, 
and the recommended method of attack. 

A part of the effort of each section is devoted to the Commercial 

development and maintenance of contact with the ernonstra " 

. ... tion. 

lumber-manufacturing and wood-using industries and 

wood consumers and producers. The resources of the 

Laboratory are made available to the public through 

personal contact with the field representatives assigned 

to study technical problems. Familiarity with the 

needs of timber growers, wood consumers, and the 

wood-using industries serves as a guide to direct the 

investigations made at the Laboratory. 

70313°— 22 2 




Timber Mechanics. 



Strength of 

Various 

Species. 



TT^NOWLEDGE of the mechanical properties of 
woods and wood products is essential for their 
intelligent and economic use, whether in the factory, 
on the farm, in the home, on the railroad, in the mine, 
or in the air. Thus development of the airplane and 
progress in many other lines depend in a large measure 
on accurate information as to the strength, toughness, 
elasticity, and other mechanical properties which de- 
termine the suitability of different woods for various 
purposes. To supply this information, over 500,000 
mechanical tests have been made, as nearly as possible 
under standardized conditions, so that the tests made 
for a single purpose will have the broadest application 
and will serve for many uses. 

Data from tests of small clear specimens are now 
available in published form on 126 species of woods 
grown in the United States and in Unpublished form 
on 23 native species, as well as data, in some cases 
meager, in some cases fairly complete, on about 60 
species, principally from South America and the Phil- 
ippines. These data are of particular value in com- 
paring the properties of the different species, in finding 
"substitutes for the scarcer and higher-priced woods, 
in selecting species for particular uses, and in estab- 



10 



Forest Products Laboratory. IX 

lishing correct working stresses. The results of these 
tests on small, clear specimens also furnish definite 
information on the variability of wood and show the 
necessity of grading timber for all uses where strength 
is of prime importance. 

A large number of tests have also been made on 
full-sized timbers, such as bridge stringers, factory- 
building timbers, and car sills. These tests have dem- 
onstrated the influence of defects, such as knots, shakes, 
and checks on strength; and, altogether with the 
results of tests on small clear specimens, furnish the 
basis for the establishment of grading rules and correct 
working stresses for structural timbers. 

Wood is subjected to a great variety of preservative Effect of 
treatments, to many different drying or seasoning Treatments 

,. . . . ' _ on Strength. 

processes, to conditioning treatments in preparation for 

bending, and to many, other processes with particular 
objects in view. Some of these treatments, particu- 
larly those which use high temperatures or high pres- 
sures, or both, appreciably lessen the strength of wood 
and are responsible for large losses. The Laboratory 
has therefore been studying the effect of such treat- 
ments on strength, with special reference to kiln- 
drying and preservative treatments, and, to a smaller 
extent, methods of conditioning wood for bending. 
Both commercial sizes and small pieces free from 
defects are used in these studies. The form and 
character of the test specimens in each case are as 
nearly standard as possible, usually varying only in 
details necessary to make the tests . directly applicable 
to the problem in hand. 

Tests have been made on plywood to determine the 
strength of different combinations of species, the effect 
of increasing the number of plies, and the effect of 
varying the ratio of core thickness to total panel 
thickness. Some data are also available on factors 
affecting warping, on strength of fastenings for ply- 
wood, on the efficiency of joints in plywood, and on 



12 



Forest Products Laboratory. 




Some of the strength-testing machines, such as the one at the right, are employed chiefly in 
determining the strength properties of native woods, using small, clear specimens like those on 
the truck. Other machines are rigged up to test wooden parts. A newly designed airplane 
wing rib is just being placed in the machine second in line. 



Forest Products Laboratory. 13 

the strength in tension. Information on such points 
as these places the Laboratory in a position to assist 
users and manufacturers of plywood and veneer prod- 
ucts in solving problems encountered in developing 
new uses for these products in the various industries. 

The results of tests on containers are of particular Tests on 

interest to all shippers, box manufacturers, and trans- n ip P! ng 

rr » L/Ontainers. 

portation companies and are also of great importance 
to the public in general. The damage due to the 
failure of containers in transportation amounts annu- 
ally to many million of dollars. There are, in addi- 
tion, large losses due to improper packing. All of the 
work done at the Laboratory in this field tends directly 
to reduce these enormous losses, which are ultimately 
paid by the consumer. A considerable amount of 
fundamental data relating to the construction of boxes 
and crates has been obtained, which finds direct appli- 
cation in the redesign of faulty containers and in the 
development of new containers. It is frequently pos- 
sible to redesign a container so as to reduce the amount 
of material required, to save shipping and warehouse 
space, and at the same time to obtain greater service- 
ability. The investigations apply to all types of both 
wooden and fiber boxes and to barrels and crates. 
One of the interesting facts established by the studies 
is that a chief source of weakness in wooden containers 
is inadequate nailing, and that the use of thicker mate- 
rial will not remedy this defect. 

Tests on various species have furnished information 
on their strength, their resistance to splitting, and their 
ability to hold nails, which has made it possible to 
classify the woods in groups for box and crate con- 
struction. 

Revolving-drum tests, together with drop and com- Drum Tests. 
pression tests of boxes loaded with either actual or 
dummy contents, have been used in determining the 
characteristic weakness of the various types of con- 
tainers. The Forests Products Laboratory standard 



14 



Forest Products Laboratory. 




The drum-testing machine, developed by the Laboratory to stimulate the hazards of transporta- 
tion, has become standard for shippers, packers, and manufacturers. The boxes shown are 
packed with electric-light bulbs. Four thousand dollars' worth of bulbs were furnished by the 
electric companies concerned for this series of tests to develop a better container. 



Forest Products Laboratory. 



15 




Aside from its value in laboratory tests, the determination of the moisture content of wood is so 
important in connection with the various uses of wood that every woodworking factory should be- 
come familiar with the simple process. A knowledge of the moisture content of the stock often 
makes it possible to avoid costly manufacturing difficulties. 



16 Forest Products Laboratory. 

drum is 14 feet in diameter and can accommodate 

packages up to 1,000 pounds in weight. It is fitted 

with hazards so arranged that the container under test 

follows a regular cycle of drops which simulate those 

received in actual transportation. The field for this 

work is very large, and much remains to be done in 

order to develop fundamental relations between the 

weight and the nature of the commodity, the type of 

box to be used, and the thickness of the bottom, side, 

and end boards. 

Tests of Tests on vehicle and implement parts, airplane parts, 

Manufac- doors, and other articles manufactured of wood are 
turedArticles. . . r r , 

made primarily to demonstrate the fitness ot substitute 

species, to develop or improve designs, and to obtain 
more economical and efficient use of wood. Consider- 
able data in published and unpublished form are now 
available on this subject. The limitations and possi- 
bilities of splices and laminated construction are being 
studied with a view to conserving lumber through the 
increased use of small pieces and low grades. This 
should make possible the use of smaller trees, which 
can be grown in comparatively short periods; in short, 
the character of material on which the country will 
have to depend very largely in the future and which 
can be grown most profitably. 





Timber Physics. 

KNOWLEDGE of the physical properties of wood 
is of importance to almost every industry using 
wood and is essential in kiln drying, impregnation 
with preservatives, distillation, and, other treatments. 
Omitting the properties already referred to as mechan- 
ical — some of which might equally well be classed as 
physical — the more distinctly physical properties 
studied are density, shrinkage, transfusion of mois- 
ture, hygroscopicity, specific heat, heat conductivity, 
heat of absorption of water in wood, and permeability 
of wood by liquids and gases. 

It is often necessary for financial reasons to reduce Kiln Dry- 
the time required properly to season wood by open-air in § - 
drying. Moreover, for many purposes it is desirable 
to dry the wood more thoroughly than is possible in 
the open air and to employ conditions which will 
reduce its hygroscopicity, or tendency to shrink and 
swell. For these reasons dry kilns are almost univer- 
sally employed for high-grade lumber, and frequently 
even for the poorer grades. In the drying of hardwoods 
it is estimated that about 10 per cent of the material 
dried is either ruined or lowered in grade. Much of 
this loss could be avoided by proper methods and kilns, 

70313°— 22 — -3 17 



Kilns. 



18 Forest Products Laboratory. 

and the present results might be greatly improved in 

other respects. 

Establishing The Forest Products Laboratory bases all its kiln- 

cienti ic d r yinpr practice on fundamental studies to determine 
rnnciples. . . 

the principles underlying the transfusion of moisture 

through wood, the effect of changes in atmospheric 
conditions upon the rate of transfusion, the effect of 
various methods of drying and of various drying treat- 
ments upon the properties of the wood being dried, 
and similar studies. In connection with this work a 
special type of kiln, known as the water-spray kiln 
and developed at the Laboratory, has found successful 
application in many commercial plants where drying 
requirements are very exacting. 

Commercial Studies of commercial types of dry kilns are well 
under way. These studies are being made to deter- 
mine the range of usefulness of the various types and 
to develop improvements wherever possible. General 
data on the cost of dry-kiln operation are also being 
obtained in so far as possible. 

Drying A comprehensive series of experiments is being con- 

ducted to determine the proper "drying schedules" for 
all important commercial woods. These drying sched- 
ules will show the proper conditions of temperature and 
humidity to obtain best results in drying, and they will 
cover the entire range from an absolutely green condi- 
tion to absolute dryness. A number of drying sched- 
ules have already been published. This class of work 
has direct application throughout the wood-using 
industries. 

In addition to schedules for lumber of various 
thicknesses, drying schedules are worked out for 
special purposes, such as the drying of gunstock 
blanks, wagon-wheel spokes, and felloes. Special 
schedules are also developed for very high-grade 
work, like the drying of aircraft stock and parts,- 
where the utmost strength is essential. Experiments 
have also been made to determine the best commercial 



Schedules. 



Forest Products Laboratory. 



19 




The distinctive feature of the Forest Service water-spray kiln is the control of the humidity in the kiln 
and, consequently, the drying rate of the lumber, by conditioning the air with sprays of water whose 
temperature is carefully regulated. The experimental kiln shown is drying oak bolster stock, which 
appears white because of the end dip used to reduce checking. 



Steam 
Bendinf 



20 Forest Products Laboratory. 

methods of drying plywood, much of the trouble in 
the manufacture of which may be traced to faulty or 
careless drying. 

The proper steam bending of heavy wooden parts, 
such as artillery wheel rims, presents a number of 
problems on which the Laboratory has done a limited 
amount of work and on which it plans to do much 
more in the near future. The proper moisture condi- 
tion of the stock, the length and temperature of steam- 
ing or other preliminary treatment, and the mechanical 
details of the actual bending must all be worked out 
before present high losses in this process can be over- 
come. 

Identi- The accurate identification of woods is important 

not only in the investigative work of the Laboratory, 
where it is essential that the kind of wood under test 
be definitely known, but to wood users generally. 
There is a steadily increasing demand in the various 
industries for service of this character, and several 
thousand specimens of wood are annually identified 
for outside concerns. Microscopic slides and photo- 
micrographs made from the slides have been prepared 
for practically all American woods of importance and 
are available for study. Authentic specimens of most 
species are also available. 

Relation of Fundamental studies under the microscope to deter- 

tructure to m j ne fa e re l a tion of structure to shrinkage have been 
. 1 roperties. t & 

under way for some time and are nearing successful 

completion. Similar studies to determine the relation 

of structure to mechanical and physical properties are 

under way, and it is hoped that structure and properties 

may be definitely correlated. 



Forest Products Laboratory. 



21 




Furniture and vehicle factories are concerned in the research of the Laboratory to reduce losses 
in the steam bending of stock. To bend a heavy wheel rim, such as is shown, without fracture, 
requires a careful preliminary conditioning treatment. 




Preservatives 



Wood Preservation. 

■ / I A HE amount of wood in the form of railroad ties, 
mine timbers, posts, poles, and other products 
which is destroyed each year by decay is approximately 
equal to the loss from forest fires. It is therefore im- 
portant to devise methods of treating wood with pre- 
servatives that will reduce this waste to a minimum. 
An annual saving of \}4 billion of board feet is esti- 
mated to be possible in the case of railroad ties alone, 
could preservative treatment be extended to the 85 
million ties at present untreated. 

In treating operations, the cost of the preservative, 
such as creosote, zinc chloride, or sodium fluoride, 
amounts to a high percentage of the total cost. Fur- 
thermore, the ultimate success of any treatment is 
largely dependent upon the preservative used. Much 
information has already been obtained concerning the 
preservatives now in common use, but there is need 
for a great deal of further study with the object of 
developing new preservatives which will either be 
cheaper or more effective than present preservatives, 
or will have properties fitting them for wider use or 
for special purposes. The value of a preservative is 
not considered established until it has had a thorough 
trial under actual service conditions. 



22 



Forest Products Laboratory. 



23 




The life of railroad ties treated with preservatives is often double that of untreated ties. The 
illustration shows some red oak ties about to undergo an experimental treatment with creosote 
in the pressure cylinder. Afterwards they will be placed in actual service in one of the test 
tracks maintained by the railroads in cooperation with the Laboratory. 



24 



Forest Products Laboratory. 




In the manufacture of water-resistant plywood with casein glue, the glue is applied cold to the 
veneer sheets by means of a mechanical glue spreader. The sheets are then placed one on top 
of another in a press. 



Forest Products Laboratory. 25 

Closely related to the work on wood preservatives Processes of 

are investigations of preservative processes. These . 

te r r tion. 

include the relative efficiency of commercially estab- 
lished processes and of new or proposed ones, as well » 
as the fundamental principles involved in the various 
conditions of temperature and pressure, and other 
factors entering in the treating process. 

A third class of wood-preservation studies deals with Suitability of 
the suitability of various species for treatment, includ- ^P ecies - 
ing the relative resistance to impregnation and decay 
and the best methods of preparing them for treatment. 

The protection of wood ap-ainst ' fire is another t?- c 

" ... . r lreproofing. 

important field in wood preservation. The annual 
fire loss in the United States is estimated at $250,000,- 
000, and is very much higher than the fire losses in 
European countries. This difference is due largely to 
the greater proportion of wooden construction in the 
United States. Fireproofing the wood or designing 
the structure so as to offer the least fire hazard are 
ways of reducing the fire loss and at the same time 
cutting down the amount of material needed for re- 
building, thus reducing the drain on our forests. 

In connection with the manufacture of plywood, Glues for 
studies have been made of animal glues, such as those 
made from hide, bone, and other products; and stand- 
ard methods of testing have been developed. A suit- 
able "standard glue" for aircraft work and high-class 
joint work in general has been developed and samples 
made available to manufacturers and users. This is 
the glue adopted as standard by Army and Navy air- 
craft bureaus. 

The development of water-resistant glues of several 
types, including casein glues and blood-albumin glues, 
has been progressing for several years, and a number 
of high-grade glues have been perfected. Tests and 
experiments are being carried forward to improve these 
glues still more, especially in their resistance to mois- 
ture. Methods of testing for the strength and water 



26 



Forest Products Laboratory. 




Wooden patterns for castings can be made practically moisture proof by an aluminum leaf coating and 
so prevented from warping, swelling, or shrinking. Car wheel patterns protected in this way are 
now in use by several large foundries. 



Forest Products Laboratory. 27 

resistance of plywood have been developed and speci- 
fications drafted for the glues and the plywood, as 
well as for the raw material from which the glues are 
made. These specifications have been adopted by the 
Army and Navy aircraft bureaus. 

One of the lines of investigation to be taken up Laminated 
recently is the determination of possibilities and best p n U1 t_u P 
practices in the design and construction of structural 
members built up of small pieces glued together. 
These investigations were carried out intensively on 
aircraft parts, such as wing beams and struts, when 
the success of the aircraft program was threatened by 
a sudden shortage of suitable material in the required 
sizes. Additional intensive work is under way on air- 
craft propellers to determine the best species to use 
and the best conditions of manufacture and allowable 
limits for specific gravity, moisture, and direction of 
grain in individual laminations. The knowledge gained 
is being applied to extensive investigations of the use of 
laminated and built-up construction in the various 
wood-using industries for the manufacture of such 
articles as shoe, lasts, hat blocks, bowling pins, wagon 
bolsters, and wheel hubs. 

The Laboratory has done considerable work on the 
moisture resistance of various wood coatings used on 
airplane propellers, and a very efficient aluminum leaf 
coating has been developed which affords protection 
against moisture over long periods of storage. Tests 
are now in progress on the durability of these coatings. 
Other work on wood finishes is contemplated. 




Processes of 
Pulp and 
Paper 
Making. 



Pulp and Paper, 

' I A HE constantly decreasing supply of suitable pulp- 
woods and the ever-increasing demand for paper 
of all kinds, especially newsprint paper, have com- 
bined to produce so serious a situation that investiga- 
tions into methods of conserving the supply of pulp- 
wood and increasing the production of paper are of 
paramount importance. 

The Laboratory is conducting experiments on 
methods of making wood pulp and has already de- 
veloped several important improvements in the stand- 
ard chemical processes. A ground-wood branch lab- 
oratory was operated at Wausau, Wis., for several 
years, at which the best conditions for grinding pulp 
were determined. The work of this laboratory was 
completed in December, 1913, and the results published 
in a series of bulletins. 
Suitability of A very important field of research lies in determining 
bpecies. t j ie su j ta bjlj t y of various little-used woods as substitutes 

for those most commonly used. Practically all avail- 
able species which give promise of suitability are being 
investigated, and proper methods of grinding or 
cooking of most of the important ones have already 
been worked out. 
28 



Forest Products Laboratory. 



29 





Special small-scale digesters for the manufacture of chemical pulp provide facilities for the study 
of pulping problems at a moderate cost, preliminary to a cooperative mill test. 



30 Forest Products Laboratory. 

Utilization Studies of waste utilization in the pulp and paper 

industry have been in progress for some time along a 
number of distinct lines. For example, feasible 
methods of turning sawmill waste, such as slabs, 
into pulp have been determined. The use*of a certain 
percentage of spent tan bark in the manufacture of 
roofing felts has been investigated and a method de- 
veloped whereby what was formerly a waste of the 
tanning industry is now in profitable commercial use. 
The possibility of using hemlock bark waste for tannin 
has also been demonstrated. 

A commercially feasible method of recovering both 
the paraffin and the fiber from waxed paper trimmings 
has been developed. Studies of the wastes incident to 
the pulp industries, such as sulphite waste liquors and 
soda liquors, in which are now carried off approxi- 
mately half of the wood that enters into the digesters, 
are to be undertaken intensively as soon as funds and 
equipment become available. The suitability for 
paper making of hull fiber and second-cut cotton 
linters, formerly of little value, has been demonstrated 
and a method of preparation worked out that has 
proved commercially successful. 

Pulp Decay. A recently begun investigation of the deterioration 
of pulpwood and wood pulp through fungous infec- 
tion, now estimated at 35,000,000 a year, is leading 
to the proper remedies for this great economic loss. 

Special Uses. 'pj^g possible use of wood pulp as a substitute for 
other material in various products has been demon- 
strated in a number of instances where the Laboratory 
has suitable equipment or where arrangements could 
be made with manufacturers. Molded articles, such 
as buttons and electrical fittings; compounds of cellu- 
lose, such as smokeless powder, lacquers, and artificial 
silk; and waterproof containers are examples of wood- 
pulp products the commercial use of which is possible 
whenever the relative costs of the pulp and of the raw 
materials in use make them practicable. 



Forest Products Laboratory. 



31 




Old newspapers can be de-inked by the use of bentonite, a highly colloidal clay, to which the ink 
particles adhere after being loosened from the paper in the pulp beater. The pulp is then ready 
to be used again in the manufacture of newspaper. 



32 Forest Products Laboratory. 

In studying the relative merits of pulps obtained 
from different woods, methods and instruments have 
been devised to determine various properties, such as 
ease of bleaching, freeness of stock, and tearing strength 
of paper. Methods of liquor analysis have been de- 
vised, and also instruments to control manufacturing 
operations, such as recording hydrometers and liquor 
samplers. 




" , '' 'ftH mill WimMMMnu : ' 



JSwp 



Derived Products. 

THE distillation of hardwoods for the production of " ard ,7° od 
r Distillation. 

wood alcohol, acetate of lime, and charcoal has 
been a well-known commercial process for many years 
and has offered one of the best methods for the utili- 
zation of hardwood wastes, such as tops, limbs, and 
slabs. The first work of the Laboratory along this 
line was a study of the comparative value of different 
species as distillation woods — at that time only beech, 
birch, and maple were used commercially. All the 
important hardwoods have been tested, and several 
new species, such as oak and hickory, are now in use. 

Methods have been developed whereby the yield of 
alcohol and acetate could be considerably increased 
by a system of temperature control without extending 
the time of distillation and with a decrease in the 
amount of fuel required. These methods have been 
adopted by most of the commercial plants. Encour- 
aging results have been obtained in work now under 
way on other methods for increasing the yields, such 
as the treatment of the wood with chemicals previous 
to distillation. 

Considerable work has been done at the Laboratory Flotation 
on methods for utilizing the hardwood tar produced s * 
by wood-distillation plants, which has so far been used 

33 



34 Forest Products Laboratory. 

almost entirely as fuel at the plants. The production 
of flotation oils from hardwood tar is a promising 
method of utilization which has been the subject of 
much investigation of the Laboratory. Several satis- 
factory flotation oils have been produced, and the com- 
mercial utilization of hardwood tar is increasing. 
Resinous The distillation of longleaf pine stump wood and 

. . • "lightwood," primarily for wood turpentine, pine oil, 

and rosin, has been a small industry for some time, 
and for the more resinous classes of waste wood it 
offers a satisfactory method of utilization. The Labo- 
ratory has carried on investigations and obtained val- 
uable results on more efficient methods for distilling 
the wood and refining the products. Other species 
than longleaf pine have also been studied, for the 
most part in test runs at commercial plants. 
Turpentine Very valuable results have been obtained by experi- 

and Rosin, mental field work in improving methods of obtaining 
crude turpentine from the tree. A new method has 
been developed which has increased the yield of tur- 
pentine and decreased the bad effect on the tree and 
reduced the danger from fire. This method has been 
adopted by almost the entire industry. A complete 
study has also been made of the amount and composi- 
tion of the turpentine from several western pines. 
The changing conditions in this industry due to the 
rapid depletion of virgin stands of longleaf pine make 
it desirable to develop turpentining methods which are 
especially applicable to second-growth timber and to 
long-continued operation on the same tree, instead of 
the usual three to five year operations. 
Ethyl (grain) A promising method of utilizing profitably large 
Alcohol. quantities of wood waste depends upon the conversion 

of the cellulose into ethyl alcohol. It has long been 
known that wood cellulose can be converted into fer- 
mentable sugar by suitable treatment with dilute acids 
at high pressures, but until recently the process has 
not met with commercial success. Investigation at the 



Forest Products Laboratory. 35 

Laboratory involved the design and installation of ap- 
paratus of semicommercial size and a detailed study 
of the influence of such variables as pressure, tempera- 
ture, time concentrations of acid and water, and many 
others. Partly as a result of these experiments the 
process is now a commercial success and offers a new 
means of utilization which will be a source of heat and 
power of immense economic importance. The two 
plants now operating in this country have a combined 
daily capacity of about 9,000 gallons of 95 per cent 
alcohol. The high quality and purity of the products 
are attested by the great demand for this alcohol for 
the preparation of pharmaceuticals and colognes. 

In addition to investigations upon the production of 
ethyl alcohol from wood, extensive studies are in 
progress upon the production of this important com- 
modity from waste sulphite liquor. The enormous 
quantity of waste sulphite liquor produced daily at 
the paper mills makes the development of a means 
of utilization of this waste material, which contains 
almost one-half of the original wood, of the greatest 
importance. 

Another study that has recently been started is the Sawdust *° r 

i • r i r i r i a • i Stock Food. 

production ot a stock food from sawdust. As in the 
manufacture of ethyl alcohol, the cellulose is first con- 
verted into sugar by treatment under pressure with 
dilute acid, and this sugar, after being extracted and 
boiled down to a thick molasses, is mixed with the 
sawdust residue. While this investigation has not 
been carried far enough to warrant final conclusions, 
preliminary experiments upon the feeding of cattle 
have been highly encouraging. This so-called "wood 
meal" has been substituted for one-fourth the ordinary 
grain ration of the cattle, with a resulting increase in 
their weight and no decrease in the yield of milk. 

Other products derived from trees or forest materials Other 
and therefore within the scope of the Laboratory's p ro d ucts 
work, are tannins, gums, balsams, essential oils ex- 



36 



Forest Products Laboratory. 




The first step in the manufacture of cattle food from sawdust is to cook the sawdust with dilute acid in 
a steam pressure cylinder. This converts a part of the wood into sugars and renders the remainder 
more digestible. Hydrolized sawdust is being successfully fed to cattle as a considerable part of 
their concentrate ration. 



Forest Products Laboratory. 37 

tracted from the wood, roots, bark, or leaves of various 

trees, and producer gas manufactured from wood. 

The chemical derivatives of cellulose, while not yet 

touched upon, also offer a fertile field for investigation. 

Fundamental knowledge of the chemical composition Chemical 
. -11 -l i ' i • -i Composition 

of any material undergoing thorough study is essential, f w 00( L 
and this need in the case of wood will eventually be 
supplied through an elaborate investigation under, way 
at the Laboratory. Methods of analysis have been 
standardized and a number of species of wood have 
been analyzed. 

The selection of the most suitable woods for the 
manufacture of separators for storage batteries and 
various kinds of chemical apparatus requires a better 
knowledge of the chemical composition and properties 
of the various woods. The more extensive utilization 
of waste wood by chemical means also depends upon 
the accumulation of data on the chemical composition 
of the different woods. The methods of analysis 
developed in this work have been of much value in 
other lines, such as the study of decay in pulpwood, 
the special use of paper pulp, and the use of hydrolyzed 
sawdust as a stock food. 



■ • . . 



Industrial Investigations, 

Mechanical A/TECHANICAL as we j| as c h em ical processes offer 

Utilization of ±\ A. • • r ^ ^ r 1 r 1 i -v • r 

Waste and a P romlsln g held i° r tne prohtable utilization ot 

Low-Grade wood now wasted and for the steadily increasing amount 
Material. Q f sma || anc | low-grade material coming from second- 
growth stands. Only 30 per cent of the wood in a 
forest now gets into the form of seasoned, unplaned 
lumber. Of this an additional 10 to 25 per cent is 
lost in the process of manufacture. In extreme cases 
as little as 3 per cent of the wood in the forest may 
reach the finished product. 
W^cTW How to reduce to a minimum these losses in logging 

and manufacture constitutes a research problem of far- 
reaching scope and significance. The Laboratory will 
undertake a comprehensive survey of the present prac- 
tice and its results in some, of the more important 
wood-using industries. This will be followed by more 
intensive investigations of equipment, methods, and 
processes with a view to determining possible modifi- 
cations and improvements. These investigations will 
be conducted both in the woods and at the mill and 
will include studies leading to increased efficiency of 
operation as well as to closer utilization. 

Dimension -p^e manufacture of small-dimension stock offers a 

Stock. . - . 

striking example of the opportunity for reducing present 

38 



Forest Products Laboratory. 39 

wastes in manufacture. It has been estimated that all 
of the 5 or 6 billion board feet used each year in the 
manufacture of articles made from such stock could 
be secured from material now wasted. Whether or 
not this is true, there is no question that present wastes 
could be greatly reduced by standardizing dimension 
sizes, by cutting dimension stock directly from the log 
instead of remanufacturing it from lumber, and by an 
interchange between industries that would result in the 
utilization by one industry of what is now regarded 
as waste in another. Studies along these lines have 
been undertaken by the Laboratory and will be ex- 
tended as rapidly as possible. 

Another problem of first importance has to do with Second 
finding a profitable and economical use for the small Stands, 
sizes and low grades on which we shall have increas- 
ingly to depend as the virgin forests are replaced by 
second-growth stands. This problem includes also the 
finding of uses for species now without markets. To 
a considerable extent the practice of forestry is depend- 
ent on developing methods by which the material of all 
species produced by these stands can be used in place 
of the high-grade material of a few species from virgin 
forests to which we have hitherto been accustomed. 
This involves not only perfecting the technique of 
built-up and laminated construction, but the introduc- 
tion of new uses and new methods of manufacture. 
Investigation of these and related problems will go far 
toward enabling us to eliminate present wastes and 
to make the most of our wood supply. 

A number of mill-scale studies have been made Mill-Scale 
, . -li i Studies and 

upon various species to determine precisely the grade, Grading 

quantity, and cost of lumber cut from logs of a given Rules. 

size and grade; and further studies of this character 

are planned. They are of direct value as a check 

upon mill efficiency and furnish a reliable basis for 

appraising the stumpage value of National Forest and 

other standing timber. Similar studies of the efficiency 



40 Forest Products Laboratory. 

and cost of manufacturing lumber will be made as an 
integral part of the comprehensive survey of equip- 
ment, methods, and processes employed by the various 
wood-using industries. Intensive studies of lumber- 
grading rules and lumber sizes, with a view to making 
them more uniform and better suited to the needs of 
the consumer will also be undertaken. 




Pathology. 

f^HE work of this section is conducted by the Bureau 
of Plant Industry of the Department of Agricul- 
ture. General studies of the durability and decay of 
wood are carried on. 

The relative durability of different woods and the 
effect of moisture and wood-destroying fungi upon the 
life of the wood have been studied for many kinds of 
American woods. Data have been obtained upon the 
least and most favorable temperatures for the growth 
of fungi and the amount of heat required to stop their 
growth. An application of this work is the control of 
so-called "dry rot" in buildings. 

The toxicity, or poisonous effect, of wood preservative 
has been studied and the antiseptic effectiveness of dif- 
ferent treatments determined. 

Extensive investigations to determine the prevalence 
of decay in buildings throughout the United States 
have been made, and from information collected over 
a 10-year period recommendations have been developed 
as to changes in architectural design, proper species for 
different uses, and suitable antiseptic treatments. 

Unsuspected losses by wood users resulting from 
improper storage of wood aggregate several million 
dollars annually. Studies and recommendations have 



Durabil- 
ity of Un- 
treated 
Wood. 



Poisonous 
Effect of Pre- 
servative. 

Decay in 
Building 
Timber. 



Sanitation 
of Storage 
Yards. 

41 



42 



Forest Products Laboratory. 




With a microscope it is possible to identify wood from practically any of our native trees. The 
revolving chart shows the diversity in wood structure brought out under a lens. 



Forest Products Laboratory. 4.3 

been made on storage of general lumber stocks at 
sawmills and retail yards, the storage of manufactured 
wood products, such as vehicle parts, boxwoods, 
veneers, and staves, and also the storage of pulpwood 
and pulp. Infection begun in the yard frequently is 
passed on in the manufactured product to other wood 
with which the infected material is used. 




How to Use the Laboratory. 



Information 
Free. 



pHE Laboratory, being a public institution, makes 
its information available to the public as rapidly 
as possible. This it does through personal contact 
and through reports written during the progress of 
investigation and upon their completion, so that all 
information of value is published, either as bulletins 
or circulars by the Government, in technical notes, by 
correspondence, or as special articles in trade journals 
and technical and scientific papers. 

Investigations are undertaken both independently 
and on a cooperative basis, but all investigations must 
be of a research character that will give information 
or results of value in attaining the general objects 
aimed at by the Laboratory. 
Cooperation. The Laboratory works in cooperation with the 
lumber-manufacturing and wood-using and timber- 
producing industries most directly concerned with the 
subjects or problems under investigation, as well as 
with State forest organizations and forest schools. As 
a general rule, no investigation conducted by the Labo- 
ratory is regarded as complete until the results ob- 
tained experimentally have been checked on a com- 
mercial scale and their industrial application deter- 
mined. 
44 



Forest Products Laboratory. 45 

This is ordinarily accomplished through cooperation 
with individuals or companies that use wood and are 
commercially interested in developing new or better 
processes or products. 

The Laboratory equipment is of experimental and 
semicommercial size, and it aims to carry results and 
ideas as close to commercial demonstrations as facili- 
ties and appropriations will permit before applying 
results at commercial plants. 

In cases of formal cooperation, there should be a Formal Co- 
remuneration to the Laboratory depending on the cost j^enSe^f 
of the work done for the cooperator, including the Company, 
time and expense of the members of the Laboratory 
detailed to the project, and its general supervision. 
When practically all of the work proposed is investi- 
gative and the results of value chiefly to the general 
public, the charge to the cooperator may be compara- 
tively low or eliminated altogether. 

Whenever practicable, arrangements are made with Material for 
cooperators or others especially interested in the inves- x P enmen s - 
tigation to furnish all the material necessary for the 
work. As far as practicable, cooperative projects are 
covered by written agreement whenever cooperative 
investigations of a specific character are to last six 
months or longer, or when the total expenditure of the 
Forest Service on the work will exceed $100. 

An arrangement which has resulted very satisfactorily in Men As- 
several cases is the assignment to the staff of the Labora- Laboratory 
tory of men from the organization of the cooperator. 

Anyone is at liberty to correspond with the Labora- Consultation 
.tory about particular problems dealing with the utili- ° n , ? e ^ 
zation of wood and will receive answers based on 
whatever information is available on the subject. The 
staff of the Laboratory is also available for consultation 
work, provided the solution of the problem under con- 
sideration will further its general research work, or has 
direct bearing upon it. 

Personal visits to the Laboratory for consultation 
have proved very satisfactory. 



46 



Forest Products Laboratory. 




Classes in boxing and crating at the Laboratory make use of the 14-foot drum testing machine 
to investigate the serviceability of shipping boxes. The manufacturers and shippers in the group 
traveled an average of 2,000 miles each to attend the one-week course. 



Forest Products Laboratory. 47 

The Laboratory has a very important function in Conserva- 

assistinp- in the conservation and utilization of National t- , " 
& # _ m est 1 lmber. 

Forest timber. It acts in a consulting capacity to the 
men in actual charge of the timber-sale work, and 
with them works out the commercial possibilities of 
blocks of timber that are ready for cutting and the 
relative value of the various species for different 
purposes. 

The design, construction, and operation of commer- Operation 

cial plants for wood preservation, distillation, kiln- ,™ mer " 
j • J-M i u J i • cial Plants, 

drying, and similar work may be undertaken in ex- 
ceptional cases when a new process will be demon- 
strated and the plant used, at least in part, for experi- 
mental work. The Laboratory may make suggestions 
regarding the construction and operation of such 
plants, referring applicants, however, to consulting 
engineers for assistance as to details. 

The Laboratory may, on request, examine the 
methods of individuals or companies used in handling 
forest products and prepare plans for improving such 
methods, provided that the purpose is primarily to 
reduce waste and to obtain information of general 
value to the industries concerned. 

Two short cooperative courses of instruction are Courses of 
given monthly at the Laboratory — one in kiln-drying, Instructlon - 
the other in boxing and crating. These courses are 
of particular value to superintendents, lumber and 
production men, and foremen in wood-using plants. 
The instruction is under the supervision of a staff, of 
competent specialists and the enrollment is limited to 
16 men in each course, so that proper attention may 
be given to individual problems. Priority of applica- 
tion governs admission to the courses, and the classes 
are usually filled for two or three months ahead. 

Detailed information concerning any of the work of 
the Laboratory will be gladly furnished. Inquiries 
should be addressed to the Director, Forest Products 
Laboratory, Madison, Wis. 

WASHINGTON : GOVERNMENT PRINTING OFFICE 11922 



LIBRARY OF CONGRESS 



DDDDflTflmab 



• 



